The Origins Space Telescope: Trades and Decisions Leading to the Baseline Mission Concept

The Origins Space Telescope will trace the history of our origins from the time dust
and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies
evolve from the earliest galactic systems to those found in the universe today? How do
habitable planets form? How common are life-bearing worlds? We describe how Origins was
designed to answer these alluring questions. We discuss the key decisions taken by the Origins
mission concept study team, the rationale for those choices, and how they led through an exploratory
design process to the Origins baseline mission concept. To understand the concept solution
space, we studied two distinct mission concepts and descoped the second concept, aiming to
maximize science per dollar and hit a self-imposed cost target. We report on the study approach
and describe the concept evolution. The resulting baseline design includes a 5.9-m diameter
telescope cryocooled to 4.5 K and equipped with three scientific instruments. The chosen architecture
is similar to that of the Spitzer Space Telescope and requires very few deployments after
launch. The cryo-thermal system design leverages JamesWebb Space Telescope technology and
experience.